Bestselling authors including Lee Child, Ian Rankin and Joanne Harris are queuing up to condemn the posting of reviews under false identities after it emerged this weekend that the award-winning crime writer RJ Ellory had been criticising his rivals and praising his own work under pseudonyms on Amazon.

Ellory, who won the Theakstons Old Peculier crime novel of the year prize in 2010 for his novel A Simple Act of Violence, was exposed by the crime writer Jeremy Duns on Twitter for posting reviews on Amazon under various identities. Under the pseudonym "Nicodemus Jones", Ellory called his own novel A Quiet Belief in Angels a "modern masterpiece" and said that readers should "just buy it, read it and make up your own mind", because "whatever else it might do, it will touch your soul". "All I will say is that there are paragraphs and chapters that just stopped me dead in my tracks," he wrote. "Some of it was chilling, some of it raced along, some of it was poetic and langorous and had to be read twice and three times to really appreciate the depth of the prose … it really is a magnificent book."

But "Nicodemus Jones" was less positive about some of his fellow novelists: Stuart MacBride was dismissed for his novel Dark Blood with one star, with the book described as "another in the seemingly endless parade of same-old-same-old police procedurals that seem to abound in the UK". Duns spotted that Ellory wrote the MacBride review under the pseudonym Nicodemus Jones, but later in the conversation began posting as RJ Ellory, in a continuation of the discussion. "Nicodemus Jones" also repeatedly signs himself as "Roger" in another discussion, in which he writes that "I won the Nouvel Observateur prize last year for AQBIA [A Quiet Belief in Angels]".

Mark Billingham was also slammed with a negative review from Nicodemus Jones, since removed, from one of Ellory's accounts. "It was just a very nasty one-star review, very snipey, saying I'd ripped off another writer and the book was just imitative," said Billingham.

Ellory has admitted posting the reviews on Amazon, and apologised for his actions, issuing a statement in which he said: "The recent reviews – both positive and negative – that have been posted on my Amazon accounts are my responsibility and my responsibility alone. I wholeheartedly regret the lapse of judgment that allowed personal opinions to be disseminated in this way and I would like to apologise to my readers and the writing community."

But Ellory is only the tip of the iceberg, according to Duns and Billingham. Two years ago, the historian Orlando Figes admitted to trashing his rivals and praising himself on Amazon, and at the Harrogate crime festival earlier this summer, the bestselling thriller writer Stephen Leather said: "As soon as my book is out I'm on Facebook and Twitter several times a day talking about it. I'll go on to several forums, the well-known forums, and post there under my name and under various other names and various other characters. You build up this whole network of characters who talk about your books and sometimes have conversations with yourself."

"[Ellory] absolutely isn't the only one," said Billingham, adding that Ellory had also apologised to him personally. "It's very widespread … And what has been most shocking about some of the more recent revelations is that up until this moment most of us had presumed that the people doing this stuff were self-published writers with no other means of marketing. But these most recent revelations prove this is not the case and it is very worrying."

"It's absolutely rife," agreed Duns. "It's so tempting, it's so easy … and it's very very hard to prove it."

The Crime Writers Association has issued a statement condemning the practice of using fake identities on blogs, Twitter or Amazon to promote a writer's own work and give bad reviews to others, calling it "unfair to authors and also to the readers who are so supportive of the crime genre", and adding that it is looking to set up a membership code of ethics.

Duns has also been helping put together an open letter from writers slamming the practice, which has been signed by names including Child, Rankin, Billingham, Val McDermid, Harris, Tony Parsons, Roger McGough, Peter James, Charlie Higson, Mo Hayder, Linwood Barclay, Andrew Taylor, Michael Connelly and others.

"Maybe we are fighting an uphill battle because it is very widespread but we are taking a stand," said Billingham. "It's an incredibly difficult thing to police though – whatever statement writers make, those intent on doing it will ignore it. [But] I hope at the very least it serves as a wake-up call to people – those who have been doing it for a while and thinking they will get away with it. At the very best [being found out] is embarrassing. At the worst it will cost people careers."

Duns suggested that sites such as Amazon could instigate a system whereby only accounts linked to Facebook pages, or to verified purchases, could post reviews. "It's not just Amazon, it's all of these sites. They have put in place these systems that are totally open to abuse, and then when people say this is going on they say we can't possibly police it."